Engineering Commons^™

Fabrication And Mass Transport Analysis Of Tape Cast Nano-Silver High Temperature Solder, Jared Ray Mccoppin

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The principal objective in this research was to develop a die attach method to facilitate the use of wide band gap semiconductors in high-temperature environments, and study fundamental mass transport in nano-initiated die attach microstructure at high temperature. Low temperature sintering silver-nano-pastes have been demonstrated as an effective method for die attach by other groups. Fabrication and optimization of the die attach method in this work was accomplished via tape casting. A novel binder system and a bimodal particle distribution were utilized. The tape casting method allowed die attach materials to be pre-stressed. Fundamental understanding of creep deformation process and …

Utility Of A Volume-Regulated Drive System For Direct Mechanical Ventricular Actuation, Benjamin A. Schmitt

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Direct Mechanical Ventricular Actuation (DMVA) is a non-blood contacting cardiac assist device that augments ventricular function. The purpose of this study was to determine if a volume-regulated "hand pump" drive system and a pressure-regulated "switch tank" drive system provide equivalent levels of cardiac support. Canine (n=2) and swine (n=4) were instrumented for hemodynamic monitoring and intravascular echocardiography. DMVA support was assessed during both severe heart failure and fibrillation. Pump function was evaluated using hemodynamic measures to calculate stroke work. Myocardial function was assessed using echocardiographic speckle tracking to quantify strain rate. Results were compared between groups using paired t-tests. There …

Assessing The Effects Of Multi-Modal Communications On Mental Workload During The Supervision Of Multiple Unmanned Aerial Vehicles, Sharon Claxton Bommer

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Human supervisory control (HSC) systems that require intermittent human input of commands to create actions within the system are helpful in reducing the human's mental workload (MWL). HSC systems are commonly employed in the piloting and control of unmanned aerial vehicles (UAVs). As the ratio of UAVs to operators increases there is a clear need to understand the effort required to complete task requirements. Specifically, this research explored MWL relative to multi-modal communications using subjective and physiological measures. To accomplish this, a cognitive model was developed to understand the relationship between tasks and MWL. MWL was manipulated by measuring three …

Application Of The Augmented Operator Function Model For Developing Performance Metrics In Persistent Surveillance, Tiffany M. Paul

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Difficulties with the implementation of persistent Wide Area Motion Imagery (WAMI) sensors to support real-time military missions have risen within Intelligence, Surveillance, and Reconnaissance organizations. In this study, cognitive models were developed of operators performing real-time missions currently supported by narrow field of view Full Motion Video (FMV) and WAMI sensors. These models were used in conjunction with a cognitive task analysis, creating an augmented operator function model (OFM-COG). This thesis describes the OFM-COG and demonstrates how this model-based analysis technique can document the cognitive implications of persistent surveillance with motion imagery. The analytic procedures required to build this model …

High-K Material Based Leaky-Wave Antenna Design, Implementation, And Manufacture, Jiahui Wang

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Leaky-wave antennas are a class of antennas which apply a traveling wave on a guiding structure as the main radiation mechanism. The properties of leaky-wave antennas are light weight, easy to fabricate, and readily integrated into conventional millimeter-wave systems. These features make leaky-wave antennas attractive. The most important characteristic is that the antenna can steer the beam direction through changing the operating frequency rather than switching the antenna itself. Variety types of leaky-wave antennas have been introduced and developed during the past 70 years. However, there is no existing leaky-wave antenna which can widely steer the beam scanning angle by …

Fabrication And Testing Of Hierarchical Carbon Nanostructures For Multifunctional Applications, Ian Timothy Barney

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Multi-scale hierarchical carbon structures have been developed by growing strongly attached carbon nanotubes (CNT) on high surface area substrates having open, interconnected porosity. This investigation was developed on cellular carbon foams but the process is equally suitable for other geometries including flat, fibers, and other porous substrates (interconnected). It is also adaptable to other substrate materials such as metals, alloys or ceramic compounds. Multiwalled carbon nanotubes are grown using a floating catalyst chemical vapor deposition (CVD) method after pre-coating the substrate with a silica nano-layer. The silica-coated graphitic substrates are seen to grow 280 times more nanotubes per unit area …

Applications Of Capillary Electrophoresis For Studying Serum Albumin Enantioselection Of D,L-Tryptophan Analogs, Jelynn A. Stinson

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The pharmacokinetic difference between drug enantiomers is the impetus for developing analytical techniques to assess enantiomeric purity. Capillary electrophoresis (CE) is an analytical technique that is used for characterizing drug-protein binding. The pitfall to using CE for drug-protein binding studies is protein chiral selectors tend to adsorb onto capillary walls and cause changes in electroosmotic flow that lead to decreased enantioselection and migration time irreproducibility between consecutive injections. The experimental parameters for minimizing the adverse effects of protein adsorption are not clear from the literature.

Rinsing protocols to improve enantioselection and migration time repeatability were developed using the tryptophan-bovine serum …

Computational Investigation Of Ethanol And Bifuel Feasibility In Solstice Engine, Adam Michael Blake

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A Gasoline Direct Injection (GDI) engine enables an increased fuel efficiency and higher power output than a conventional Port Fuel Injection (PFI) system. By injecting pressurized fuel straight into each cylinder of an internal-combustion engine, the degree of fuel atomization is increased, as well as the fuel vaporization rate. In order to further harness the effects of direct injection, ethanol is implemented as a fuel. The cooling effect of ethanol fuel droplets changing to vapor inside the combustion chamber facilitates a higher compression ratio, thus increasing engine power and efficiency. Three dimensional computational simulation is used to investigate the feasibility …

Application Of The Human-Machine Interaction Model To Multiple Attribute Task Battery (Matb): Task Component Interaction And The Strategy Paradigm, Craig M. Walters

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The Multiple-Attribute Task Battery (MATB) is composed of four simultaneously running components to which a human operator responds. A prior report has quantified information content as a machine input baud rate using the Hick-Hyman and Fitt's Laws for three of the four components and defines a strategy function. This report covers methods to quantify information content of the fourth component, creating a single metric which describes overall task complexity and evaluates human performance and strategy. Six MATB task-scenarios (combinations of two, three, or all four MATB components) each at two input baud rates are evaluated. Subjects were also provided with …

Regulation Of The Transcription And Subcellular Localization Of The Tumor Suppressor Pten By Δnp63Α, Mary Kathryn Leonard

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Non-melanoma skin cancers (NMSCs) are the most common form of cancer in the United States with an estimated 3.5 million new cases each year. Surgical excision is the main treatment for NMSC, but leaves the potential for disfiguring scars and does not fully reduce the risk of recurrence since the surrounding tissue is also sun damaged and may contain tumor-promoting mutations. By understanding the molecular etiology of NMSC we may be able to expand treatment options to more than just resection. Normal epidermal development is dependent upon the expression of the transcription factor p63. Amplification of the ΔNp63α isoform is …

Characterization Of Doped Gallium Nitride Substrates, Jack Lee Owsley Iii

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In this thesis the characteristics of five bulk semi-insulated doped gallium nitride samples provided by Kyma Technologies, Inc were explored. The five GaN samples were grown on sapphire substrates by hydride vapor phase epitaxy (HVPE) and doped with different concentrations of iron, hydrogen, carbon, oxygen and silicon. The first step of characterization was measuring the optical absorption of all the samples using a UV-NIR fiber spectrometer. Through this procedure it was found that they all showed a strong absorption at 518 nm. Thus, time-resolved differential transmission measurements were conducted at this wavelength using the second harmonic generation (SHG) of a …

The Demonstration Of Smse Based Cognitive Radio In Mobile Environment Via Software Defined Radio, Ruolin Zhou

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With the emergence of increasing number of wireless devices and demands for higher data rates, spectrum crowding and congestion increases. Spectrum congestion problem has been challenging wireless communication engineers for a few decades. However, recent studies indicate that most of the time wide ranges of the radio spectrum are rarely utilized. Hence, the spectrum congestion is mainly due to the inefficient spectrum usage rather than the spectrum scarcity. To exploit under used spectrum and utilize the spectrum efficiently in dynamically changing environments, a new technology is needed. Cognitive Radio (CR) arises to be a possible solution to spectral crowding problem …

A Basic Understanding Of Rapid Mold Surface Heating Via Laser Energy, Charles Daniel Fox

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As the research and development of surface heating methods have increased in the recent years, the consensus has been reached amongst the injection molding community that an elevated mold surface temperature near or greater than the polymer solidification temperature provides acceptable replication of the desired micro-structured parts. The laser heating experimental work and simulation development carried out includes two sample sizes similar to those used in injection molding. A 100W CO2 laser incident on three samples of different surface roughnesses has shown to have elevated temperatures via thermal cameral data and thermocouple measurements. Among five different laser spot sizes varying …

Nano-Scale Rf/Microwave Characterization Of Materials' Electromagnetic Properties, Joshua Allen Myers

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There are two words that describe the direction of today's electronic technology, smaller and faster. With the ever decreeing size scientists and engineers must have a way to characterize materials in the nm range. In this thesis characterization of nano-materials is discussed based on scanning probe microscopy and an in-depth look at RF/microwave frequencies by scanning microwave microscopy. Recently, low-temperature spin-sprayed ferrite films (Fe3O4) with a high self-biased magnetic anisotropy field have been reported, showing FMR frequency>5 GHz. Such films hold great potential for RF/microwave devices and find immediate applications. In this study, we performed in situ scanning microwave …

Optimization Of Wsu Total Ankle Replacement Systems, Bradley Jay Elliott

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Total ankle arthroplasty (TAR) is performed in order to reduce the pain and loss of ambulation in patients with various forms of arthritis and trauma. Although replacement devices fail by a number of mechanisms, wear in the polyethylene liner constitutes one of the dominating failure modes. This leads to instability and loosening of the implant. Mechanisms that contribute to wear in the liners are high contact and subsurface stresses that break down the material over time. Therefore, it is important to understand the gait that generates these stresses. Methods to characterize and decrease wear in Ohio TARs have been performed …

Computational Investigation Of A Hinge-Connected Hovering Plate, Zachary Robert Gaston

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A simplified conceptual flapping wing MAV design, capable of hover, is formed from the works of both biologists and engineers, studying the behavior of flying insects and the aerodynamics of flapping flight. With this new model, hovering hinged plates are used to study the effects of passive deflection on aerodynamic performance using two-dimensional Direct Numerical Simulations (DNS) at low Reynolds numbers (Re). The hinge is modeled as a torsional spring at the leading edge, where prescribed motion is applied. The influence of forced-to-natural frequency ratio (hinge stiffness) and stroke-to-chord ratio (leading edge kinematics) are studied, to explore the effects that …

Human Action Recognition By Principal Component Analysis Of Motion Curves, Daniel Stephen Chivers

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Human action recognition is used to automatically detect and recognize actions per- formed by humans in a video. Applications include visual surveillance, human-computer interaction, and robot intelligence, to name a few. An example of a surveillance application is a system that monitors a large public area, such as an airport, for suspicious activity. In human-machine interaction, computers may be controlled by simple human actions. For example, the motion of an arm may instruct the computer to rotate a 3-D model that is being displayed. Human action recognition is also an important capability of intelligent robots that interact with humans.

General …

An Optimization Approach To Indoor Location Problem Based On Received Signal Strength, Lei Zheng

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This research was motivated by the desire of a Fortune 100 retail company to track its customers' behaviors through the implementation of a low-cost indoor location system using received signal devices. Indoor location through received signal strength (RSS) is of low costs, yet it suffers from poor accuracy due to lack of direct line-of-sight, multi-path ratio propagation, and various interferences. To improve its location estimation accuracy, therefore, we propose a mathematical programming based propagation approach for RSS based location systems. The core of our approach is an optimization model that minimizes the sum of squared errors of signal strength. In …

A Unified Nonlinear Adaptive Approach For The Fault Diagnosis Of Aircraft Engines, Remus C. Avram

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In this thesis, a fault detection and isolation (FDI) method is developed for aircraft engines by utilizing nonlinear adaptive estimation techniques. Engine sensor faults, actuator faults and component faults are considered under one unified framework. The fault diagnosis architecture consists of a bank of nonlinear adaptive estimators. One of them is the fault detection estimator used for fault detection, and the remaining ones are fault isolation estimators employed to determine the particular fault type/location after fault detection. Each isolation estimator is designed based on the functional structure of a particular fault type under consideration. The FDI architecture has been integrated …

Mapping Algorithm For Autonomous Navigation Of Lawn Mower Using Sick Laser, Shashidhar Baichbal

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The objective of this thesis is to present a mapping algorithm for autonomous navigation of a lawnmower based on the range and bearing information of a SICK laser. The Simultaneous Localization and Mapping (SLAM) algorithm is a tool that can be used to navigate unmanned vehicle in an unknown environment. The two-dimensional (2D) maps of the obstacles can be obtained if the laser scans the environment in a plane horizontal to the ground. However, the 2D map does not give information of the objects that are placed below the height of the laser. This makes it difficult for the lawn …

Behavioral Signature-Based Framework For Identifying Unsatisfiable Variable Mappings Between Digital Designs, Vaibhav Uday Tendulkar

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Throughout its design process (from specification to implementation) a digital circuit goes through a variety of structural changes. These changes are introduced primarily due to the use of automated tools in the design process. Checking whether the Boolean functions representing the two designs are equivalent is thus necessary to verify if a design implementation adheres to its specification. Combinational Equivalence Checking (CEC) - a process of determining whether two combinational design functions are equiv-alent, has been one of the most researched Boolean matching problems. The well-known CEC techniques that have been proposed adopt some kind of a formal approach such …

Key Factors Influencing The Structure And Electrochemical Performances Of Lifepo4 Via Sol-Gel Synthesis, Chuang Guan

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Olivine structured LiFePO4 is a promising cathode material for the next generation of lithium ion batteries for its low cost, environmental benign, good cycling performance and safety, etc. However, its intrinsic poor electrical conductivity and diffusion capability of lithium ion greatly hinder its application in the high power recharge battery. In this research, a cost-effective sol-gel method was used to synthesize carbon coated LiFePO4 (LiFePO4/C) materials. The influences of the synthesis parameters, including the species of iron source, lithium content, chelating agents and carbon sources, PH value of the sol, and sintering conditions etc., on the structure and electrochemical properties …

The Role Of Amp-Activated Protein Kinase (Ampk) In Hypoxic Chemotransduction By The Carotid Body, Heidi Lynn Jordan

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The carotid bodies are small sensory organs located along the bifurcation of the carotid arteries. They detect changes in blood gases and relay this information to the brain to allow for initiation of appropriate respiratory and cardiovascular responses. A decrease in oxygen (hypoxia) sensed by the carotid body results in an increase in firing of the carotid sinus nerve and ultimately a change in one's breathing pattern. An inability to respond to an acute hypoxic (low oxygen) episode via increased ventilation may result in death or lead to pathological or chronic conditions such as stroke and hypertension (Prabhakar et.al., 2005). …

Modeling And Simulation Of A Dynamic Turbofan Engine Using Matlab/Simulink, Scott Michael Eastbourn

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A dynamic, high-bypass turbofan engine has been developed in the modeling and simulation environment of MATLAB/Simulink. Individual elements, including the fan, high pressure compressor, combustor, high pressure turbine, low pressure turbine, plenum volumes, and exit nozzle, have been combined to investigate the behavior of a typical turbofan engine throughout an aircraft mission. Special attention has been paid to the development of transient capabilities throughout the model, increasing model fidelity, eliminating algebraic constraints, and reducing simulation time through the use of advanced numerical solvers. This lessening of computation times is paramount for conducting future aircraft system-level design trade studies efficiently, as …

Measurement Of Static And Dynamic Performance Characteristics Of Electric Propulsion Systems, Aron Jon Brezina

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Today's unmanned aerial vehicles are being utilized by numerous groups around the world for various missions. Most of the smaller vehicles that have been developed use commercially-off-the-shelf parts, and little information about the performance characteristics of the propulsion systems is available in the archival literature. In light of this, the aim of the present research was to determine the performance of various small-scale propellers in the 4.0 to 6.0 inch diameter range driven by an electric motor. An experimental test stand was designed and constructed in which the propeller/electric motor was mounted in a wind tunnel for both static and …

The Role Of Angiotensin Converting Enzyme (Ace) 2 In A Murine Model Of Insulin Resistance And Albuminuria, Nathan Michael Weir

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Insulin resistance and kidney disease are intimately linked and both independently tied to dysregulation of the renin angiotensin system (RAS). The purpose of this research was to better investigate Angiotensin Converting Enzyme (ACE) 2 as a possible motif in the pathophysiology of these two disease processes. The project was divided into two parts. Part 1 investigated ACE2 KO mice as a model of albuminuria. Part 2 investigated how the lack of ACE2 enzyme affected glucose homeostasis and subsequent albuminuria.

Part 1: The Role of ACE2 in the Progression of Albuminuria. To determine if global loss of ACE2 leads to spontaneous …

Effect Of Cooling Rate And Mold Counter Pressure On The Crystallinity And Foaming Control In Microcellular Injection Molded Polypropylene Parts, Jeffrey Scott Cousineau

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Microcellular polymer injection molding is a growing industry technique due to its ability to produce dimensionally stable stress free parts while reducing cycle time, material usage, and energy costs. The process was invented by Dr. Nam P. Suh at the Massachusetts Institute of Technology in the early 1980's. The basic idea is to dissolve a supercritical fluid into the polymer melt which will nucleate and expand within the part core after injection during the cooling stage. Microcellular polymer injection molding is becoming increasingly popular in automotive, semiconductor, and industrial applications. While the technique has been widely successful using amorphous polymers, …

Structural And Electronic Properties Of Two-Dimensional Silicene, Graphene, And Related Structures, Ruiping Zhou

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Traditional CMOS (complementary metal-oxide-semiconductor) transistors have already been in the nanometer range. As bulk silicon material is approaching its physical limits, it is highly desirable to seek novel, functional materials to continue Moore's law. Two-dimensional(2D) materials, such as graphene and silicene, have attracted great attention since they were envisioned a few years ago, having extraordinary electrical properties. Research in this work was focused on understanding the structural and electronic properties of a few atomic layers of carbon (graphene) and silicon (silicene). Atomic structures of the 2D materials, corresponding band structures, and transport properties were calculated based on density functional theory. …

Isothermal Deformation And Modeling Of Ti-6al-4v, Vamsi Krishna Vempati

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Ti-6Al-4V has attractive properties such as high strength to weight ratio, good fatigue properties and excellent corrosion resistance and these properties have made this alloy an important material for the aerospace industry. In this thesis, the deformation behavior of Ti-6Al-4V with several processing histories, was studied by conducting isothermal constant strain rate compression tests over a temperature range of 829°C to 996°C (1525°F to 1825°F) and at strain rates of 10-2 s-1, 10-1 s-1 and 100 s-1. True stress versus true strain flow curves showed a peak stress followed by flow softening. The data was analyzed to obtain constitutive equations …

Ultra Low Power Read-Out Integrated Circuit Design, Jian Chen

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Carbon nanotubes (CNTs) are widely studied by the researchers in recent years, as they have small size, large strength, highly electrical and thermal conductivity. The single-walled CNT (SWNT) is readily changed in electrical resistance when exposed to gas, and has significant use in environmental monitoring, agriculture and fishing industry, chemical industry and even security. A read-out integrated circuit (ROIC) is required to detect the resistive change. In this thesis, an ultra-low power, wide dynamic detecting range and small size CMOS ROIC design is presented. This ROIC can interface wide dynamic range signal up to more than two orders (100pA-60nA) from …